Endurance testing machine for springs



Nov. 26, 1940, F. WUNDERLICH 2,222,

ENDURANCE TESTING MACHINE FOR SPRINGS Filed July 1, 1.93s

f .1 5G I '1. m 22 I 19 23 nun W Patented Nov. 26 1940 I 2,222,892-

UNITED STATES PATENT OFFICE 20 springs ENDURANCE TESTING MACHINE FOR SPRINGS Friedrich Wunderlich, Stuttgart, Germany, as-

signor to Robert Bosch Geselischaft mit beschriinkter Haftung, Stuttgart, Germany ApplicationJuly 1, 1938, Serial No. 217,057 In Germany July l6, 1937 1 Claims. (01. 73-51) The present invention relates to fatigue or endurance testing machines for springs, of the type wherein a plurality of springs which are to be tested at the same time are stretched beg tween beams which are movable relative to each other. v

The purpose of the invention is to produce an endurance testing machine of this type which makes it possible, by corresponding loading of a lo plurality of springs of identical kind'which are stretched at the same time, to determine in a single continuous test the so-called Wohler curves for changing load. According to, the- 25 which:

Figure n a diagrammatic arrangement of the subject of the invention.

Figure 2 is a side elevation of a modified form -of construction, and Figure 3 is a section on theline m-m in Figure 2.

On a pint, which-is arranged so as to be.

stationary, there are 'rotatably mounted two beams 2, 3 which run roughly parallel to each 35 other when in the inoperative position shown. Springs are inserted in recesses 4 in the beams.

To the lower end of the beams 2, 3 are pivotally connected levers 6, I, which are connected witha crank mechanism 8, 9. As soon as the 40 crank gear is set into motion, for instance by can electric motor, the pair of levers 8, -'l fiexes upwards and downwards alternately out of the middle position shown. When this occurs, the beams 2, 3 approach each other and move away 5 from each other and exert a changing strain upon. the springs 5. During this procedure,

the lowest spring will urry out a larger throw than the other springs, and the top spring is leaststressed. By this means, given equal con- 50 stitution of all the springs, the lowest spring becomes broken more quickly than the others, then follows the next spring, and so on, while it is appropriate so to dimension the springs that the top spring, which is least loaded, does 5 not become broken even after many million disposed side by side.

changes of load. Now, itis only necessary to determine after how many changes of load or minutes or hours the separate springshave successively become broken, and by this means the data for drawing up the known Wiihler 5 curves for materials which are submitted. to c{hanging stress are obtained directly. Since- ,the springs are generally not manufactured so exactly that one spring always has the same properties as another spring which has been .1

manufactured in exactly the same way, it is suitable, in order that the stray values may not have an unfavourable influence on the result of the examination to construct the beams of such width that several springs are always For instance, five further springs of the same kind may be stretched in the same way behind each of the springs 5 shown in Figure 1.

In another form of construction according to Figures 2 and 3, two beams or plates ll, 2|.

which are parallel to. each other, are firmly disposed on four stanchions i0. At the left of v Figure 2 is shown a pedestal bearing l2, about the-pin l3 of which an oscillating beam 14 is.

set into to and fro movement by a crank mechanism l5, IS. The throw of the crank gear, l5, It can be adjusted by means of a radially adjustable slide block l1. Spring plates [5a are fitted on the oscillating beam l4. Between the spring plates I511. and recesses H3 in the plates .II are inserted a number of springs IS, the right hand ones of which are deflected more by the crank mechanism I5, l6 and those on the left are deflected less by the said mechanism. Thus, with this arrangement, the right hand springs l9 will break more quickly than those disposed further to the left.

The spring plates l5a are pivotally connected with the oscillating beam It by pins 20. Fur- 40 'ther, by means of a pin 22 and a rod- 23, a pivotal connection is made between the spring plates lid and a pin 24 which is flrmly disposed in the pedestal bearing l2. vBy this means, there arises a parallelogram guide l3, I4, I50, 22, 23, 5'

24 which ensures that, on its upward and downward movement by the crank mechanism, the spring plate Iia can never get out of its vertical position. In this\ way, undesired influences.

which might otherwise arise with the crank drlve as a result of one ofthe ends of the springs getting into an oblique position, are avoided.

. Care should further-be taken to ensure that" thespacing of the pin I3 from the spring I9 disposed next to it is not too small, so that the height of the arc described on the oscillation about the pin 13 can be practically neglected.

While the beams I i and 2| according to Figure 3 are constructed for the use of several rows of springs side by side as comparatively wide plates, the appropriate oscillating beam 14 is not constructed as a uniform plate. The oscillating beam 14 for the separate rows of springs are rather broken up into a number of separate beams a, Mb, I40, etc.; this has the advantage of making it particularly simple to assemble the spring plates Ia.

I declare, that what I claim is:

1. An endurance testing machine for springs, comprising two relatively movable beams between which a plurality of springs to be simultaneously tested are arranged endwise with their ends in contact with said beams at spaced points along said beams whereby said springs will be contracted and expanded by oscillation of one beam relative to the other, said two beams being arranged parallel to each other when in the inoperative .position, and means to oscillate said beams in such a way that the stresses on the individual springs are difierent from spring to.

spring corresponding to the difierent throw of different points along the beams.

2. An endurance testing machine for springs, comprising two relatively movable beams between which a plurality of springs to be simultaneously tested are arranged endwise with their ends in contact with said beams at spaced points along said beams whereby said springs will be contracted and expanded by oscillation of one beam relative to the other, said two beams being arranged parallel to each other when in the inoperative position, a stationary bearing iri-which one of said beams is mounted, and means to oscillate said one beam relatively to the other beam so that the stresses on the individual springs are diflferent from spring to spring corresponding to the different throw of different points along the beams.

3. An endurance testing machine for springs,

comprising two fixed beams, an intermediate osalong the beams.

4. An endurance testing machin for springs comprising two relatively movable beams arranged parallel to each other when in inoperative position, a plurality of movably arranged supporting surfaces on at least one of said beams adapted to support the ends of springs, arranged between said beams at spaced points along said beams whereby said springs willbe contracted and expanded by oscillation of one beam relative to the other, and means to oscillate one of said beams in such a way that the stresses on the.individual springs are difierent from spring to spring corresponding to the different throw of different points along the beams.

v 5. An endurance testing machine for springs, comprising two relative movable beams arranged parallel to each other when in inoperative position, a plurality of movably arranged supporting surfaces on at least one of said beams adapted to support the ends of springs, arranged between one of said beams at spaced points along said beams whereby said springs will be contracted and expanded by oscillation of one beam relative to the other, a parallelogram guide connected to said supporting surfaces to-keep the same parallel, and means to oscillate one of said beams in such a way that the stresses on the individual springs are difierent from spring to spring corresponding to the different throw of difierent points along the beams.

6. An endurance testing machine for springs, comprising two relatively movable beams, between which a plurality of springs to be simultaneously tested are arranged endwise with their ends in contact with said beams at spaced points along said beams whereby said springs will be contracted and expanded by oscillation of one beam relative to the other, said two beams being of such a width that several rows of springs can be arranged side by said and being arranged parallel to each other when in the inoperative position, and means to oscillate one of said beams in such a way that the stresses on the individual springs are difierent from spring to spring corresponding to the different throw of different points along the beams.

"I. An endurance testing machine for springs, comprising two relatively movable beams :between which a plurality of springs to" be simultaneously tested are arranged endwise with their ends in contact with said beams at spaced points along said beams whereby said springs will be contracted and expanded by oscillation of one beam relative to the other, said two beams being arranged parallel to each other when in the inoperative position, one of said beams comprising a comparatively wide plate and the other of said :beams being divided into a plurality of connected beam portions which aremoved jointly, and means to oscillate one of said beams relatively to the other insuch a way that the stresses on the individual springs are different from spring to spring corresponding to the different throw of different points along the beams.

' FRIEDRICH WUNDERLICH. 

